Silver protecting cloth and process of making the same



United States Patent SILVER PROTECTING CLOTH AND PROCESS OF MAKING THE SAME Adolph Renold, Springdale, Conn assignor to Bates Manufacturing Company, a corporation of Maine No Drawing. Application March 11, 1952, Serial No. 276,065

26 Claims. (Cl. 252-192) This invention-relates'to a process for preparing silver protecting cloth and to a composition for use in this process and, more particularly, to processes for applying waterinsoluole silversalts totextiles which avoid the necessity ofprecipitating such salts in situ in the textile, and to compositions for use in such processes, and to the products thereof- Silver protecting cloth has come into wide use as a wrapper for silver to prevent it from tarnishing. The most desirable tarmsh-proofing agents for silver appear to besilver salts.

TheGrinnell Jones U. S. Patent- No. 1,766,646, dated- June 24; 1930, describes silver protecting cloths in which silver salts are the tarnish-proofing agents. According to the d1sclos ure of this patent, silver salts are particularly desirable, inasmuch as they react quickly and completely with hydrogen sufide and the like sulfur-containing gases inv much thesame manner as'silver itself to produce an insoluble. silver sulfide. In this way, such gases are kept from reaching the silver articles-Wrapped in the cloth.

In the process described in the Grinnell Jones patent, the (210th is first impregnatedwith a solution of a-soluble silver salt, such as silver nitrate, and squeezed to remove the excess of silver nitrate solution. Then without drying the cloth a hot alkaline solution of sodium carbonate isapplied. thereto, causing the silver to be precipitated on and in the cotton fibers as a solid insoluble adherent compound of silver. The cloth then is rapidly Washed with Water to remove all excess alkali and other soluble substances. This process, although describedusing silver nitrate and sodium carbonate as.illustrative, is infact.

terial'and presents a very largesurface of silver compound for contactwith the tarnishing gases. I

This-procedure of forming theinsoluble silver salt in situ on the. cloth has the-disadvantage that there are.

present soluble salts. which fail to react or are formed as aby-product ofthe reaction. Silver plate may become damaged through electrolytic action if a soluble salt comes into contact therewith. Therefore, it is necessary to remove any residual soluble salts by-careful washing, but usually it is impossible-to remove all'of the soluble salts, and. in consequence, they are deposited on the cloth along with the insoluble silver salt when the cloth is dried.

Washing presents the additional objection that some of the insolublesilver salt may be washed out mechanically, as

well as the soluble material.

Although the productproduced in-accordance with theprocess of the Grinnell Jones patent has been recognized as very effective from the standpoint of protecting silver,

attempts have been made to modify the process and thus.

overcome ditficulties'which it presents.

One improvement noted in the literature on the method patented by Grinnell Jones appears in U. S. Patent No. 2,003;333 to Kenneth H. Barnard and Henry F. Kane. These investigators pointout that the Jonesprocess 'produces a brownproduct whose color isso strong. as to overpower other dyes. This difficulty is overcome'by theruse In fact, the disclosure and the claims- "ice of silver ferrocyanide, precipitating it in situ in'the cloth by interaction of two solutions ina process very similar to Grinnell Jones, employingyellow prussiate of soda' in place of the sodium carbonate mentioned by Grinnell Jones. A colloid is present in the solution in order to cause the formation of a finely divided precipitate. The- The precipitation is carried out in a precipitating tankor jigger in the presence of the cloth, which has previously been impregnated with the silver nitrate. It is evident that this development is a specific application of the Grinnell Jones process to different silver salts and withtheadded presence of a colloid. The product is a cloth impregnated with a silver salt formed in. situ thereon.

Another modification of the Grinnell Jones process, which likewise results in the formation of a silver protecting cloth impregnated with an insoluble silver salt; is described in Patent No. 2,136,483 to KennethH; Barnardand Arthur F. McLean, datedNovember 15,1938; The solutions are reacted au dehors the fabric in this process, and the precipitate of insoluble silver salt is dissolved byaddition of ammonia. This solution then is applied to the textile cloth and the cloth is dried, whereupon the ammonia evaporates and the insoluble silver'salt is pre cipitated. This method has the disadvantage of requir ing the use of large quantities of ammonia, which presents a handling and recoveryhazard due to the ammonia s unpleasant odor and toxicity. Moreover the solutions are not appreciably less alkaline than the sodium carbonate solutions employed by Grinnell Jones.

Soluble-salts are precipitated with the silver salt on-the fabric, and must be washed out by the same troublesome Washingprocedures described by Grinnell'Jones. Also, the silver" salt precipitated on the cloth isnot bound thereto in-any way, except as the precipitating procedure may elfect the extent to which the particles are within the fibers of' the cloth, and the clothhas a tendency to dustyjust as in the'caseof the Grinnell Jones product H Another modificationof the Grinnell Jones process is describedin Patent No. 2,480,930 to Elwood C. Jackson and? Tully H. Babb, dated September 6, 1949. Jackson. and Babb point out that the process of the. Barnard et ala Patent'No. 2,003,333 indeedhas the disadvantage of requiring two steps; and the supplemental difficulty thatsilver salts present in the cloth maydissolve out in thesecond bath and precipitate in the solution insteadofonl the'fabrie. In order to avoidthis, Jackson and Babb pro-- pose to precipitate'the silver ferrocyanide au dehorsthe cloth as in.the Barnard and McLean process and apply the solution: containing-the finely divided precipitate. to the cloth. Thesolution contains locust bean. gum in order to assure the formation of afinely divided precipi tate. However, these investigators admit that the final mixture which isapplied to the cloth containssilver ferro cyanide and sodium nitrate, audit is evidentin consequence that when the cloth is dried it may contain appreciablequantities of soluble sodium-nitrate,- which are-- ditficult to remove by washing.v

The instant invention providesa process and composition useful in producing. silver. protecting cloth which avoids the difficulties of. all-of the prior processes described above in that soluble saltsare never present and therefore need-not be removed from the treated cloth by special procedures. The soluble salts are: eliminated by forming a dispersion comprisingtfinely divided waterinsoluble silver salt starting with the water insoluble silversalt-rather than by forming the insolublesilver salt by reaction of two soluble salts asin the GrinnelJones: process and the Barnard et al. and Jackson et al. processes following it.

In one-preferred embodiment, this dispersion contains a binder which adheres the insoluble silver salt to the cloth, and overcomes the dusting difliculties attributable to nonbinder-containing products heretofore available. There is obtainable Withthis dispersion a textile producthaving a water-insoluble silver salt distributed thereon' and adhered thereto by the binder.

Heretofore. it has beenthought impossible to prepare aqueous dispersions of water-insoluble-silver salts except by precipitation of the silver salt in situ, desirably in-the presence of acolloid. In'accordance with theinstant invention, however, a-concentrateddispersion containing a finely divided water-insoluble silver salt is formed by dispersing the insoluble silver salt in a grinding liquid in the presence of a filler which can function both as a grinding aid in reducing the silver salt to a dispersible particle size and as a protective colloid or dispersing agent for the silver salt. This dispersion can be diluted with water to form an aqueous disperslon of a solids content suitable for direct application to a text1le to produce a silver protecting cloth without applying at the same time any of the soluble by-product salts WhlCh have led to difficulties heretofore.

The invention makes possible the treatment of textiles with any water-insoluble silver compound, including the oxide and salts of inorganic and orgamcacids. Typical water-insoluble silver salts com ng within the scope of the invention are silver iodate, silver pyrophosphate, silver carbonate, silver palmitate, silver stearate, silver metaphosphate, silver orthophosphate, silver ferricyanide and silver ferrocyanide.

The filler employed in conjunction with the s lver salt has a dual function. It assists in reducing the silver salt to a finely-divided particle size and thus serves as a grinding agent. In addition, in the presence of water, the filler takes on the character of a protective colloid or dispersing agent, and assists in dispersing thefinely divided silver salt in the aqueous medium and maintaining it in dispersed form. Materials which have been found satisfactory as fillers include natural starches, such as corn, sago, maize, cassava, arrowroot, wheat and potato starches, and modified and incompletely hydrolyzed starches, such as the dextrines derived from cassava, corn, potato, sag-o and wheat starches, and converted or modified corn starch.

The silver salt can be reduced to the desirable finelydivided form by grinding it with the filler in a conventional ball. roll or pebble mill. A three-roll mill can be used, for example, with the rolls set at less than 0.0001 inch clearance. Those skilled in the art know other suitable grinding methods and apparatus. In general, it may be stated that equipment useful for reduc ng pigments to a finely-divided form for dispersion in paints can be employed in the instant invention.

It is desirable to have a grinding liquid present to assist the grinding and to serve as the dispersing medium for the silver salt. Water is quite satisfactory for this purpose and is preferable because it also is the preferred dispersant for the diluted dispersion which is applied to the textile. A grinding oil may be more effective than water in preparing dispersions of higher solids contents. Liquid detergents such as any of those listed hereinafter and especially nonionic detergents, e. g., alkyl aryl polyether alcohols such as Triton X100 (polyethylene glycol-octyl alcohol reaction product) can also be used as the grinding liquid. Other suitable liquid detergents are polyethylene glycol esters of rosin, and polyethylene glycol ethers of alkylated phenols as exemplified by the Hercules synthetics B-48, B-79 and B97.

Grinding oils are well known to those skilled in the paint art, and any of these known oils can be em loyed. For example, modified linseed oils, as exemplified by Trimol No. 80, and soya oil-maleic anhydride reaction products, as exemplified by Soya Trimol No. 4, and

mineral oil have been found satisfactory.

From 0.5 to 2 parts of filler per part of silver salt by weight make possible the production of a stable, concentrated dispersion. From 0.5 to 2 parts of grinding liquid, which may be water, grinding oil or a liquid detergent, per part of silver salt should also be used. These ranges represent satisfactory minimum proportions. Optimum proportions are 1 part silver salt to 1.7 parts grinding liquid to 1 part filler.

Only as much filler and grinding liquid as is necessary to disperse the silver salt should be used. Although the stated proportions of filler and grinding liquid to silver salt may be greater than those stated, larger quantities of those materials are not necessary. In fact, excessively large quantities are to be avoided, for the silver salt may be enveloped in filler and/or grinding liquid, if the latter is not volatile. after depostion thereof on the textile, and hydrogen sulfide then would be kept from reaching and reacting with the silver salt, thus defeating the purpose of the composition.

To the concentrated dispersion there can be added from 0.5 to 1 part of a protective colloid per part of silver salt. This component is not essential and the proportions thereof are not critical, but its presence assist in making a smooth dispersion which remains suitable for long periods. Protective colloidswhich have given satisfact-ory results in this respect are'methyl cellulose and sodium carboxymethylcellulose.

When water and like volatile liquids are used as the grinding liquid, no difiiculties are encountered, either in the grinding procedure or in the preparation of the aqueous dispersion from the concentrate, and textiles treated with such dispersions show excellent protection to silverware. However, some dusting of silver salt may occur.

To avoid this, it is especially desirable to include a binding agent in dispersions in which water or other volatile liquid is employed as the grinding liquid, although a binder can be used with advantage when nonvolatile grinding liquids are employed as well. This material can be used at a concentration within the range from 0 to 45%. Modified alkyd resins are preferred binding agents. Suitable binders are: Trimol No. (linseed oil, maleic anhydride reaction product), Trimol No. 4 (soya oil maleic anhydride reaction product), Rezyl 387-5 (short oil oxidizing type soya modified alkyd resin dissolved in xylene), Aroplaz 1273 (vegetable drying oilmodified phthalic anhydride-pentaerythritol alkyd resin), and Arofiat 3050P40 (vegetable drying oil-modified pentaerythritol-alpha, beta-ethylenically unsaturated dibasic acid alkyd-resin).

In some instances, a material which is useful as a grinding oil will also be useful as a binder. For example, some soya oil-maleic anhydride reaction products have binding properties. When the grinding oil has the properties of a binder, it is not necessary to include a sup lemental binder in the dispersion.

The concentrated dispersion prepared as described above containing silver salt, filler and grinding medium may have too high a solids concentration for convenient application to a textile. In this event it is preferable to dilute the concentrated dispersion with water. The dispersion should be of such a solids content that it will not be viscous and when applied to the cloth at a 50 to wet pickup by weight, there will be provided from 0.2 to 2.5% silver metal by weight on the cloth. More than this may be applied if desired, but it is not necessary. In order to preserve the hand of the cloth, it is desirable to keep the total solids applied to the cloth below 10% and usually in the range from about 1% to about 7% by weight of the cloth. Usually these conditions are adequately met by a dispersion having a solids content of not over 12% by Weight. Such dispersions are not very viscous and give a good total penetration throughout the is poured slowly into a vessel containing approximately one-third of the water required to produce a dispersion of the desired solids content, at room temperature, while agitating violently and with injection of live steam. In the course of addition of the concentrated dispersion, the temperature of the water is increased to nearly the boiling point, i. e., between to 200 F., and the diluted dispersion is held at a temperature within this range for about five minutes which allows the filler to assume the character of a protective colloid and maintain the silver salt in dispersed form in the aqueous medium. The dispersion is then quickly cooled to room temperature.

Other dilution procedures may be employed, but it is important to avoid breaking the emulsion in which the silver salt is held in suspension.

In order to avoid damage to the textile, it is usually desirable that the diluted aqueous dispersion which is applied thereto not be acid. On the other hand, at too alkaline a pH the silver salt may be hydrolyzed. Therefore, it is preferable that the pH of the diluted dispersion lie within the range from about 7 to about 8. Since the concentrated dispersion containing the ingredients set forth above usually has a pH slightly on the acid side, in order to bring the pH of the concentrated and of diluted dispersions prepared therefrom to within the range set forth, it is necessary to add an alkaline material to either dispersion. The alkaline material should be volatile, so that it will be removed when the fabric which has been padded with the dispersion is dried. Satisfactory volatile alkaline materials are ammonium hydroxide and the organic amines of lower molecular weight, such as morpholine, ethylamine, propylamine,

bntylamine, diisopropylamine, pyrrolidine and diethylamine- .To facilitatewetting. of. the. textile. by the dispersion a. small. amount. of. a. wetting. agent. or detergent, usually not over. approximately. 1%. by weight, canbeadded'to either. the. concentrated or. diluted. dispersion. Non-ionic wetting agents and detergents-are preferred,. suchv as. alkylated aryl'polyether alcohols, e. g., polyethylene glycol,- octyl alcohol reaction products, as exemplified by Triton X-100, polyethylene glycol esters of rosin, sorbitan monolaurate, palmitate and stearate, polyoxyethylene derivatives (the Tweens), polyoxyethylene stearate, caprate, laurate andoleate, ethylene oxide condensates with fatty alcohols and fatty acids, glycerol mono.- stearate, and" fatty acid-amine ester condensates. A wide variety of nonionic wetting agents are known to those skilled in the art and therefore further details. need not besetforth herein: Anionic'and cationic wetting agents also may be used, if desired; with goodresults; however, they must not be reactive with silver. For this reason, they. mustnot. contain chloride ion, or sulfur.

Additional optional materials include antifoamers such as. mixtures of paraflin wax and glycerol monostearate and silicone resins, and driers such as cobalt, and lead naphthenates, which can also be added as desired.

Some grinding oils have strong odors and may impart an. undesirable odor to the silver protecting cloth; This disadvantage may be overcome by incorporating a small quantity of the order of :5 to 1% of a deodorant oil or perfume in the concentrated or diluted dispersion. Some drying oils and modified alkyd resins are odorless and therefore do not. present this problem. However, when modified alkydresinsare employed it is desirable to. incorporate additional quantities of organic solvents to facilitate preparation of the dispersion, and cobalt or. leadnaphthenatedriers should alsobe added.

As stated, theconcentration of the diluted dispersion with. respect to silverandv the wet pick-up of. the cloth are adjusted so. that. there will be provided at least 0.2% silver, calculated as the metal, by weight of the textile. Obviously, in meeting this requirement, the proportions of silver compound present in the diluted aqueous. dispcrsion will be varied in relation to the percentage of silver in the silver salt employed. It will be evident that the quantity ofsilver stearate required will belarger thanthat of silver carbonate or silver pyrophosphate; because of the lower proportion of silver in silver stearate.

The following table shows in terms of silver pyrophosphate the composition of various diluted. aqueous dis-. r

persions containing a binder which can be. prepared, using water, binder and wetting agent as the grinding liquids. The amount of silver pyrophosphate can, by calculation, as those skilled in the art are aware, be changed to accommodate other silver compounds'from a knowledge: of. the silver. content. of the other compounds, and byincreasingor decreasing the amounts of filler, binder and other ingredients accordingly in accord with the recommended proportions of these materials to silver compound heretofore, set forth.

TABILE'I Silver pyrophosphate per cent solids 16.2-43.7 Filler -d0 16.5-35.2 Binder -do 0.0-453 Alkaline. material do' 0.1-4.3 Wetting agent; do 1.333.0 Parts; of: water to each part of above concentration 7.3- 17 9 8.5; Triton Xl00' Example I A concentrated. dispersion of. silver pyrophosphate ina grinding oil (SoyaTrimoliNot 4:) was: prepared. by grind: ing a mix having the following composition:

by three passes. in. a. three-roll. mill. with. theclearance set at 0.0001 inch.

The: concentrate; was; poured: slowly" into a: tank containing-about onez third of thezwnter neededzto' dilute the concentrateto t a;- dispersionz having: a. 2.46% silver pyro'e phosphate content. This was done while: the? water; at room.- temperature, was agitated violently by injecting live. steam, with stirring. The. tcmperaturewasbrought nearly to. boiling. and held. thereforabout 5 minutes: The steam, was then. turned. 011:. and. a. quantity: oft cracked ice equal. tov about. one-third. the. total weight of water was added. with, stirring. Tap. water. at.v roorm tempera? ture: was then. added. to. bring. the. dispersiom to; the..- cor..- rect volume. Morpholine; perfiune, methyl cellulose and Triton. X.1.00. were. addedto. form. a final. dispersion of pH 7 having the following composition:

Percent Silver pyrophosphate: 2246 White dextrine 0:50 Converted corn starch 119'6 SoyaTri'rnol No'. 4 (soya oil-maleic anhydridereaction product) 3:310 M'orpholine 0.32 Perfume 0120 Methyl cellulose 1.35 Triton X-l00 (condensation product of octyl phenol and polyethylene. glycol (8-12.,mols. ethyleneoxide).). 2.0.0. Water 87.94

This dispersion was padded on maroonflannel 0'31 wet pick-up by weight and dried, thusidepositingg 1.23% silver pyrophosphate by weight on the. cloth, the: cloth then was given a light remapping. The'fiannelfhad good hydrogen sulfide absorbency and a good hand." Little change in color of the flannel was observed.

Example 2.

Silver pyrophosphate wasground. with modifiedistarch, white dextrine and Rezyl 387-5 (a short oil oxidizing type pure alkyd resin dissolved in xylene) morpholine. and Triton X- to"prepare a concentrated dispersion: of the silverpyrophosphate" of' the following" composi tion, in whichthe'alkyd resin and xylene serve: as the: grindingmedium:-

Percent: Silverpyrophosphate- 33.6 White dextrine 429 Modified cornstarch; 19.5 Rezyl 387-5 (modified alkyd. resin. dissolved in.

xylene) 2'7..f5= Xylene 311' Morpholine 0.7 Triton X-100. 1017 Examplei Aaconcentrated':dispersion"was'prepared'oft silver. pyro-x phosphate; in: TritonaX-IOO having: the following; com" position, using;the:three ro1l mill of-' Example; 1:.

Percent Silver pyrophosphate 44.0 Modifiedxorn starch. ,2 1.9 Morpholine, 1L2.

"7 This composition wasdispersed in water using the procedure described in Example 1, and to this dispersion was added an antifoaming agent (silicone resin antifoamer) resulting in a dispersion of the following composition:

Percent Silver pyrophosphate 2.00 Modified corn starch 1.00 Morpholine 0.005 Triton X-100 1.50 Antifoaming agent (silicone resin antifoamer) 0.005 Water 95.44 pH 7 to 8 A second dispersion was prepared which was identical with the above, with the exception that 1.5% of an alkyd resin was added. This dispersion had the following composition:

Percent Silver pyrophosphate 2.00 Modified corn starch 1.00 Morpholine 0.005 Triton X-100 1.50 Rezyl 387- 1.50 6% Cobalt drier 0.012 Antifoaming agent (silicone resin antifoamer) 0.005 Water 93.928

Each of these dispersions was padded on a flannel cloth to a 110% wet pick-up by weight and dried. The cloths after remapping in each case had a good hand and showed excellent hydrogen sulfide absorption, giving good protection to silverware enclosed therein. The cloth padded with the composition containing alkyd resin (Rezy1 3875) showed no tendency to dust.

' Example 4 A concentrated dispersion was prepared of silver pyrophosphate m water having the following composition:

Percent Silver pyrophosphate 48.1 Modified corn starch 24.1 Morpholine 1.9 Triton X-lOO 1.9 Water 24.0

This concentrate was dispersed in water as described in Example 1 to produce a dispersion to which antifoam was added, having the following composition:

Percent Silver pyrophosphate 2.00 Modified corn starch 1.00 Morpholine 0.079 Triton X-lOO 1.50 Antifoarning agent (silicone resin antifoamer) 0.005 Water 95.416 pH 7 A second dispersion was prepared which was identical with the above, but contained 1.5% of an alkyd resin. This dispersion had the following composition:

. Percent Silver pyrophosphate 2.00 Modified corn starch 1.00 Morpholine 0.079 Triton X-100 1.50 Rezyl 387-5 7 1.50 6% Cobalt drier 0.012 A'ntifoaming agent (silicone resin antifoamer) 0.005 Water 93.904

pH 7 to 8 Each of these dispersions was padded on a flannel cloth to a 110% wet pick-up by weight and dried, after which the cloth was given a light remapping. The cloths hada good hand and gave good protection to silverware wrapped therein. The cloth padded with the dispersion which contained alkyd resin showed no tendency to dust silver salt.

Example 5 concentrated dispersion was prepared using mineral oil'as the grinding liquid and initial dispersant, and having the following composition? r Percent Silver pyrophosphate 34.7 Modified corn starch 17.4 Morpholine 1.3 Triton X-l00 V 1.3 Mineral oil 45.3

This concentrate was diluted with water as described in Example 1 and to the resulting dispersion an antifoaming agent was added. The dispersion had the following composition:

Percent Silver pyrophosphate 2.00 Modified corn starch 1.00 Morpholine 0.075 Triton X- 0.075 Antifoarning agent (silicone resin antifoarner) 0.005 Mineral oil 2.615 Water 94.230 pH 7 to 8 This dispersion was padded on a flannel cloth to a wet pick-up by weight and then dried. The cloth after remapping had a good hand and gave excellent protection to silverware wrapped therein.

Example 6 A concentrated dispersion was prepared of silver stearate in alkyd resin, xylene and liquid detergent (Triton X-100) using the three-rollmill of Example 1 and having the following composition:

Percent Silver stearate 35.2 Modified corn starch 25.8 Morpholine 0.5 Triton X-100 7.9 Rezyl 387-5 21.7 Xylene 8.9

This concentrate was dispersed in water as described in Example 1, and to the resulting dispersion a solution of a modified alkyd resin in xylene, an antifoaming agent and cobalt drier were added to produce the following dispersion:

Percent Silver Stearate 2.46 Modified corn starch 1.81 Rezyl solution 387-5 1.52 Xylene 0.62 Morpholine 0.03 Triton X-l00 0.55 6% cobalt drier 0.012 Antifoaming agent (silicone resin antifoamer) 0.005 Water 92.993

This dispersion was padded on a flannel cloth to a 50% wet pick-up by weight. The dry flannel had a good hand and definitely prevented the tarnishing of silverware enclosed therein.

In order to provide a cloth with the long life of a cloth treated with a dispersion containing 2% silver pyrophosphate the silver stearate content of the above dispersion should be increased to about 5.1% due to the smaller per cent of silver contained in silver stearate.

Example 7 The following example shows that dispersions having very low concentrations of silver salt can be employed when applied at a wet pick-up of 100% or more. The concentrated dispersions were prepared of silver pyrophosphate in Triton X-100, and then diluted with water as set forth in Example 1. These dispersions had the following composition:

aromas Each: of:- these: dispersions; was padded '1 one flannel. a 11.1%. wet. pick-mp; by weight: The; clothsywere dried, and: given a. light renapping.-; Dispersion A..yieldedja treated cloth; containing 0.42% silver, by calculation, from the weight of silver salt :the .ein, dispersionB; a clo.tl1' containing 02% silver,.by calculation, anddispersion C a..clothcontaining;0.1% silver, by. calculation. The first two cloths gave. adequate protection against- 31111811 to silverware enclosed therein. The. clothobtainedfrom dispersion Cjdid not. give good silve'raprotection; the silver becoming tarnished within approximately, 4 hours' after an exposure-of 1*. cubic; centimeter; of. hydrogen sulfide perrhn, showing that:about:0.2% silver is theeffective minimum foradequateprotection;

Example 8' A concentrated dispersion of silver iodate-in alkyd resin and-liquid'detergent (Triton X-100) wasprepared having the following composition:

Percent Silver iodate" V 33.5 Modifiedcorn starch 35; Rezyl 387- 21.9 Xylene 0.9 Morpholine 0.5 Triton X400 8,

Example 9 A concentrated 1 dispersion. of. silver; carbonate in. alkyd resin and liquid detergent (Triton-X400) was prepared having-the :following composition:

Percent Silvercarbonate I v 38.7 Modified corn starch .28.1 Rezyl 387-5 24.1 Morpholine 0.5 Triton X-100 8.6

This concentrate was dispersed" in waterinthe ratio of 1 part to 13131parts-of waten. Theresultmg disperslon, which had PH of about 7, was padded on, a. flannel cloth to a 50% Wetpick-upbyweight, after which the cloth was given a light-renapping; The cloth had-a good hand and excellenthydrogensulfide absorption; giving extremely good hydrogen-sulfideprotection to silverware enclosed. therein; with no dusting being..evidenced...

Example 10 The following-is an example of a;diluted aqueous; dispersion'of 'silverpalmitate:

Percent Silver palmitate 1.75 White dextrine 0.60 Alkali-modified corn starch 0.60

Trimol No. 80 (linseed oil-maleic anhydride reaction product) 1.75 Morpholine 0.20 Deodorant 0.10 Methyl cellulose 0.66 Triton X-100 1.00 Silicone resin antifoaming agent 0.05 Water 93.29

pH about 7 This dispersion, upon application to a flannel cloth at a 100% pick-up by weight, drying and renapping, produces a silver protecting cloth which shows excellent hydrogen sulfide absorption and gives good protection to silverware enclosed therein.

In the above examples, in many instances a particular liquid or liquid mixture is referred to as the grinding liquid. Actually, however, all of the liquids present in the grinding mix can in a sense be collectively regarded as the grinding medium, since it is very difiicult to determine the exact state of the dispersed silver salt when a mixture of liquids is used.

The process of the invention can be applied to textile fabrics of? all kind.s:. 'V IiOUS1mQdQSFof'pliepalingifliei extiles.fen-impregnation canlie-used, and it'wlllibfltun-o derstoodthat any such; methods as-arez known; to those skilledinthe art are'contemplated as.=.within.the; varia-. tionszoftthez invention. Thelproeess is-applicable: to texa tile 'fabrics in; the greige; and:.to dyedv textile: fabrics; Itwill bev foundthat; as; a-general. rule. the color. of the. dyd;fabric .-is littleafiectedby the-process ofthe in-. vention, pro videdthe. total. amount of composition. by weight of 'theafabric doesgnot exceed-the amountsrecome mended;.herein.

If desired, When greige or; bleached: fabrics are being: treated, pigments may beincorporated: in the: dispersion or the compositionof; thednventionto; produce a-.colored cloth. ln thiscvent, however, his especially important to employ the minimum= quantities required: of: filler in: order to, obtain. the a maximum effect from the pigments incorporated therein.

The following exampleisillustrative; of a pigment containing composition:

Example. 11 A concentrated" dispersion of silver pyrophosphate in a grinding oil (Soya Trimol No. 4.) was prepared using a three-roll mill according to the followingfortnulation:

Parts. i verpyrop osp ate--- Modified corn starch 80 White dextrine 20 Soya Trimol No. 4 174.8: AtlanticRed Toner (organic. red pigment) 81.3

Per. cent Silver pyrophosphate; 1.23 White dextrine 0,.25. Alkali-modified corn starch 0.98 Atlantic Red Toner 1.00l SoyaTrimol No. 4 2.15 Morpholine I 0.16 Deodorant 0.10 Methyl cellulose. 0.75 Triton X-l00 1.00 Water; 92.38

This. dispersion. was;padded on; a. flannel to a. 100%.. wet-.pick-up ,-by weight and.dried,,thus depositing 1.23%: silver pyrophosphate by weight; onthe cloth, and the. clothgivenalightirenapping, The flannel had a'good; red= color-,excellent hydrogen sulfide absorbency and a, good: hand.

If: a; shade other: than red. is; desired, other-suitable colon pigments, can; be used, following the: same pro.- cedure.

It is evident from the above description that only the silver salt, filler and grinding liquid are the essential ingredients of the concentrated dispersion, and that the other components, i. e., the binder, wetting agent, antifoaming agent, protective colloid, driers, alkaline material, etc. can be added to either the concentrated dispersion or the diluted dispersion, as may prove convenient, or can be omitted entirely.

In many of the examples given the dispersions are designed to be applied to the textile material at a 50% wet pick-up by weight. It will be understood that the concentration of the dispersions can be modified for a 100% wet pick-up by weight merely by cutting the concentrations of the various components in half. This, for example, can be done with the compositions of Examples 1, 2, 6, 8 and 9. On the other hand, by doubling the concentrations of the components in Examples 3, 4, 5, l0 and 11, the wet pick-up can be reduced to 50% by weight. Those skilled in the art will readily perceive that in this way dispersions adapted for any wet pick-up by weight can be prepared.

All proportions and percentages in the specification and claims are by weight.

I claim:

1. A textile-treating composition for producing silver protecting textile material, comprising a water-insoluble silver compound reactive with hydrogen sulfide and a solid filler-grinding aid selected from the group consisting of natural starches and modified and incompletely hydrolyzed starches in the proportion of at least onehalf part filler-grinding aid per part of silver compound but less than will render the silver compound unavailable for reaction with hydrogen sulfide,- after deposition on a textile, the silver compound and filler-grinding aid being ground and dispersed together in finely-divided form in a drying oil in the proportion of at least one-half part drying oil per part of silver compound, said composition being free from water-soluble salts.

2. A composition in accordance with claim 1 in which the silver compound is silver pyrophosphate.

3. A composition in accordance with claim 1 in which the silver compound is silver stearate.

4. A composition in accordance with claim 1 in which the silver compound is silver carbonate.

5. A composition in accordance with claim 1 in which the silver compound is silver iodate.

6. A composition in accordance with claim 1 in which the drying oil is a soya oil-maleic anhydride reaction product.

7. A composition in accordance with claim 1 which also includes a volatile alkali in an amount less than will dissolve the silver compound but sufiicient to bring the pH-of a dilute aqueous dispersion of the composition to within the range from about 7 to about 8.

8. A composition in accordance with claim 7 in which the alkali is morpholine.

9. A composition in accordance with claim 7 in which the alkali is ammonia.

10. A composition in accordance with claim 1 which includes from one-half to one part, per part of silver compound, of a protective colloid in addition to the filler-grinding aid.

11. A composition in accordance with claim 1 in which the filler-grinding aid is a dextrine.

12. A composition in accordance with claim 1 in which the filler-grinding aid is a natural starch.

13. A composition in accordance with claim 1 which includes up to 45% by weight of the solids content of the composition of a synthetic resinous binder in addition to the filler-grinding aid. I

14. A composition in accordance with claim 13 in which the binder is an oil modified alkydresin.

15. An aqueous textile-treating dispersion for use in producing silver protecting textile material comprising a water-insoluble silver compound reactive with hydrogen sulfide, a solid filler-grinding aid selected from the group consisting of natural starches and modified and incompletely hydrolyzed starches in the proportion of at least one-half part filler-grinding aid per part of silver compound but less than will render the silver compound unavailable for reaction with hydrogen sulfide after deposition on a textile, the silver compound and filler-grinding aid being ground and dispersed together in finely-divided form in a liquid dispersing medium in the proportion of at least one-half part liquid per part of silver compound, and a resinous binder in an amount up to approximately 45% by weight of the solids content of the dispersion in addition to the filler-grinding aid, said composition being free from water-soluble salts. I

16. A dispersion in accordance with claim 15 which includes a volatile alkali in an amount less than will dissolve the silver compound but sufficient to bring the pH to within the range from about 7 to about 8.

17. A dispersion in accordance with claim 15 which includes a wetting agent.

18. A process of preparing silver silver-protecting textile material which comprises applying to the material a dispersion in accordance with claim 15 and then drying the material.

19. A textile material having distributed thereon and adhered thereto a composition comprising a water-insoluble silver compound reactive with hydrogen sulfide and in a condition available for such reaction, and a filler-grinding aid selected from the group consisting of natural starches and modified and incompletely hydrolyzed starches in the proportion of at least one-half part filler-grinding aid per part of silver compound but less than will render the silver compound unavailable for reaction with hydrogen sulfide, the silver compound and filler-grinding aid having been ground and dispersed together in finely-divided form prior to deposition on the textile, and a synthetic resinous binder in an amount up to approximately 45% by weight of the composition, said textile material being free from water-soluble salts.

20. A textile material in accordance with claim 19 in which the silver compound is silver pyrophosphate.

21. A textile material in accordance with claim 19 in which the silver compound is silver stearate.

22. A textile material in accordance with claim 19 in which the silver compound is silver carbonate.

23. A textile material in accordance with claim 19 in which the silver compound is silver iodate.

24. A textile material in accordance with claim19 in which the binder is an oil modified alkyd resin. 25. A textile material in accordance with claim 19 in which the binder is a soya oil-maleic anhydride reaction product.

26. A composition in accordance with claim 15 in which the binder is an oil-modified alkyd resin.

References Cited in the file of this patent UNITED STATES PATENTS 1,972,323 Shiraelf Sept. 4, 1934 2,184,310 Meigs Dec. 26, 1939 2,434,190 Barnes Jan. 6, 1948 2,480,930 Jackson Sept. 6, 1949 2,500,113 Banks Mar. 7, 1950 2,527,261 Hart Oct. 24, 1950 2,550,345 Gray Apr. 24, 1951 2,565,418 Yackel Aug. 21, 1951 2,600,719 Wood July 17, 1952 

1. A TEXTILE-TREATING COMPOSITION FOR PRODUCING SILVER PROTECTING TEXTILE MATERIAL, COMPRISING A WATER-INSOLUBLE SILVER COMPOUND REACTIVE WITH HYDROGEN SULFIDE AND A SOLID FILLER-GRINDING AID SELECTED FROM THE GROUP CONSISTING OF NATURAL STARCHES AND MODIFIED AND INCOMPLETELY HYDROLYZED STARCHES IN THE PROPORTION OF AT LEAST ONE HALF PART FILLER-GRINDING AID PER PART OF SILVER COMPOUND BUT LESS THAN WILL RENDER THE SILVER COMPOUND UNAVAILABLE FOR REACTION WITH HYDROGEN SULFIDE AFTER DEPOSITION ON A TEXTILE, THE SILVER COMPOUND AND FILLER-GRINDING AID BEING GROUND AND DISPERSED TOGETHER IN FINELY-DIVIDED FORM IN A DRYING OIL IN THE PROPORTION OF AT LEAST ONE-HALF PART DRYING OIL PER PART OF SILVER COMPOUND, SAID COMPOSITION BEING FREE FROM WATER-SOLUBLE SALTS. 